1. Field of the Invention
The present invention relates to rail seats for rails which have a lower patten provided on both sides with upper contact surfaces, with a fibbed plate which is connected to a support by fastenings and to push-down elements for retaining the rail.
2. Discussion of Related Art
The generic rails are in this case rails of all kinds, particularly rails or points in a railway or tramway system. However, rails in another logistic or transport system, for example in the field of warehousing or mining, may also be retained with the seating according to the invention. For this reason rail within the meaning of this application may be understood to refer to any rail of a rail-bound transport system. In this case, rails used have a lower patten provided on both sides with upper contact surfaces. The rail seat is provided with a so-called ribbed plate, which is connected to a support by fastenings and with sprung push-down elements retained on the rib plate, which elements are supported on the support surfaces for retaining the rails.
Such a rail seat is disclosed in the company brochure “Environmental protection in rail transport” from the company Clouth Gummiwerke AG. The rail seats of the prior art are used both in the region of the ballast superstructure and in the so-called “solid railroad system”. In both cases vibrations due to unavoidable wheel and railroad unevenness must be compensated for in order to increase driving comfort on the one hand and minimise rolling noises on the other.
For this purpose the rail seats of the prior art have intermediate plates underneath the rail seat. These include an elastic material and absorb the load generated by the passing train. Underneath the intermediate plate is provided a support which may be formed either from an iron plate to which the remaining parts of the rail seat can be screwed, or from a concreted-in seating element. This seating element may then form part of the “solid-railroad system” or a sleeper, for example.
Furthermore an elastic intermediate layer, generally includes synthetic rubber, is arranged between the patten and the ribbed plate to prevent vibrations.
The rail seats of prior art are connected to the rails by two or more push-down elements. The rails normally have the shape of a “double-T” bracket, the upper running surface being designed thicker and the lower patten thinner, but wider for this purpose. The upper side of the laterally projecting pattens in this case serves as a support surface for the push-down elements, which in most cases are screwed on one side to the ribbed plate in the form of a wire strap, and are pushed onto the support surface with a laterally projecting region due to the force of the screw. This retains the rail. A lateral support on each side of the patten can additionally fix the rail, which is particularly appropriate at high speeds or on curves.
Although the rail seats of the prior art are able to retain the rail safely, they nevertheless have two disadvantages. Firstly, the elasticity of the intermediate layer and the intermediate plate is often insufficient, particularly in the tramway sector. Therefore it is often necessary to provide the possibility of spring deflection of the rail by up to 4 mm in tramway construction with modem crocodile cars, which possibility should also be provided in the region of the rail seats to avoid unsteady travel due to non-flexible seats.
Moreover, the assembly, and in particular the disassembly of the rail seats of prior art are very expensive. The screw connections of the push-down elements must be tightened or loosened by large square wrenches, and in this case loosening in particular may be very difficult after years of influence in most cases from thawing salt, rain or metallic rail abrasion. Because of the influence of forces associated with forceful loosening the rail seat is also often damaged so much that it has to be fully replaced. For this purpose a large area of the rail once again has to be loosened to be able to remove the entire rail seat.